Experimental Study On Mechanical Properties Of Red Clay Improved With Diash

China’s industrial waste fly ash is piled up in the open air,causing serious pollution to the environment.Guizhou belongs to karst landform and red clay is widely distributed.If red clay is used as subgrade filling,red clay pavement will appear longitudinal cracks along the road,because red clay has dry shrinkage cracking.In the project,the stability of the red clay slope is extremely poor,which has an extremely adverse impact on the project,and even threatens the safety of people’s lives and property,and affects the operation of the project and social and economic development.At present,more scholars have studied red clay.Red clay has a certain region,and the nature of red clay in different regions is quite different.According to the above problems,the red clay of lime-fly ash / cement-fly ash.Adding lime-fly ash / cement-fly ash with different mixed ratios,systematically studied lime-fly ash / cement-fly ash,improved the physical and mechanical properties of red clay,and obtained the following research results:(1)The relationship between lime-fly ash / cement-fly ash was obtained,the mix ratio and unconfined compressive strength,and the preliminary mix ratio of lime-fly ash and cement-fly ash were determined.(2)Through the compaction test of 16 groups of lime-fly ash-red clay and the nonlateral limited compressive strength test,the maximum dry density of the improved red clay is smaller than that of the plain red clay,while the optimal water content is large,and the unlimited compressive strength has increased.When the fly ash content of the lime-fly ash-red clay is 25%,the nonlateral compressive strength reaches the maximum.(3)Through 12 groups of cement-fly ash-red clay compaction test and unlimited strength test,the maximum dry density of the improved red clay is smaller than that of the maximum water content of the improved red clay.When the ratio between the cement and fly ash is 1:2.5-1: 3.0,the unrestricted compressive strength reaches the maximum.(4)plain red clay water stability is very poor,immersed water is prone to collapse.The water stability is improved by adding lime-fly ash / cement-fly ash;if a certain amount of water glass is added,the improved red clay water stability will be further improved.(5)In general,the shear strength index c,φ of red clay is affected by the compaction degree and moisture content.When the greater the compaction degree,the greater the cohesion force and internal friction angle of the red clay,and when the moisture content gradually increases,the adhesion force and inner friction angle also decrease.(6)The shear strength index c,φ of lime-fly ash-red clay / cement-fly ash-red clay soil is greatly influenced by the curing age and moisture content.After the curing period reached 28 d,the shear strength index of lime-fly ash-red clay / cement-fly ash-red clay basically reached a stable state.The three-axis stress-strain curve of lime-fly ash-red clay / cement-fly ash-red clay presents a strong softening type with brittle destruction.The research results in this paper can provide technical reference for subgrade engineering construction,make full use of industrial waste fly ash,use industrial waste fly ash to improve red clay,solve the environmental pollution problem of fly ash,has some practical engineering significance.